Machine for rolling screw threads



Jan. 27. i925. I 1,524,327

G. H. WAYNE MACHINE FOR ROLLING SCREW THREADS Filed Aug. 30. 1923 2SheetsSheet 1 M25 W W h l/ 23 W o o f/ ll IIIIH IIIHHHHIII I Iii! I I ilwvewtoz 1524,327 G. H. WAYNE MACHINE FOR ROLLING SCREW THREADS FiledAug. 30. 192; 2 Sheets-Sheet f2 avwemtoz Patented Jan. 27 1925.

UNITED STATES PATENT OFFICE.

GLENN H. WAYNE, OF WATERBURY. CONNECTICUT, ASSIGNOR 'IO SCOVILL MANU-FACTURING COMPANY, OF WATERBURY, CONNECTICUT, A CORPORATION OF GON-NECTICUT.

MACHINE FOR ROLLING SCREW THREADS.

Application filed August so, 1923. Serial No. 660,061.

To all whom it may concern:

Be it known that I, GLENN H. WAYNE, a citizen of the United States,residing at Waterbury, county of New Haven, and State of Connecticut,have invented certain new and useful Improvements in Machines forRolling Screw Threads, fully described and represented in the followingspecification and the accompanying drawings, forming a. part of thesame.

This invention relates to machines for rolling screw threads.

In the formation. of screw threads by rolling, a round blank is causedto roll between two threading dies which have relative movement. Thesedies have complementary series of thread-forming teeth and during thetravel of the blank between the dies the metal of the blankis upset intothe form of a screw thread.

In the use of thread-rolling machines as heretofore known there has beena considerable loss due to products which have to be rejected because ofinaccurate, or what is known commercially as drunk threads.

It is the principal object of the present invention to provide a machinefor rolling screw threads such that the threads produced are uniformlyaccurate within the limits of deviation allowed by trade standards. Asis more fully set forth hereinafter, the inaccuracies referred to aredue to what may be termed a slippage of the blank with respFctto thedies. It is more particularly an object of the present invention toprovide a thread-rolling machine so constructed as to compensate forthis slippage and thus produce. more accurate threads.

With this general object in view the invention consists in thecombinations, details of construction and arrangements of parts whichwill first be described in connection with the accompanying drawings andthen more particularly pointed out.

In the drawings Figure 1 is a plan view, with parts in section, of athread-rolling machine constructed in accordance with the invention;

Figure 2 is an enlarged view of part of the same, with parts broken awayand in section;

Figure 3 is an end view looking in the direction of the arrow in Fig. 2,with parts in section;

Figure 4 is a sectional view (enlarged) taken on the line 44 of Fig. 2,looking in the direction of the arrow;

Figure 5 is a similar View showing more or less diagrammatically certainof the parts shown in Fig. 4 in a different position;

Figure 6 is a sectional View taken on the line 66 of Fig. 2; and,

Figures 7, 8 and 9 are exaggerated explanatory views of dies and blanks.

Referring to the drawings, the invention in its entirety includes twocomplementary dies for rolling threads on a blank which rolls betweenthe dies as the thread is formed. The blank may be rolled between thedies by relative movement of the dies and the dies may conveniently beflat blocks, one block being reciprocated with respect to the other.Although capable of various constructions. in that here shown as anexample, slidable in upper and lower tracks 11. 12 of a bed block 1?, isa slide 14 having a die-carrying portion 15. This latter carries a flat.substantially rectangular die block 16 which rests on a, ledge 15 of thecarrier 15 and is secured in place by means of clamps 17 and bolts 18.The outer ver tical face of this die block has a series of teeth 19,hereinafter referred to. To reciprocate the die 16, as here shown as anexample, secured to "he slide 14 is the end of a pitman 20 "driven froma disk 21 by a crank pin 22 mounted therein. Disk 21 is rotatablyconnected with a gear 23 meshing with a pinion 24 on a drive shaft 25.This shaft is rotated by a pulley 26 to which power may be a plied inany suitable manner. As the drive shaft rotates the slide 14 is movedforward and back in its bed block thereby to cause endwise reciprocation.of the die block.

to have a slight compensating movement,

' means.

hereinafter described,.but as distinguished from the traveling movementof die 16, the second die is stationary. In the exemplific cation hereillustrated, carried by a frame or bed block 27 is a supporting block 28located opposite the slide 14 and adjustably held in position by bolts29. The block 28 has a ledge 28 on which is supported a die carrier 30which is held in place by clamps 3i and bolts 32. Mounted in the diecarrier 30, in a manner hereinafter described, is a flat, substantiallyrectangular die block 33 located on a level with the die 16, as appearsin Fig. The outer vertical face of the die block 33 is formed with aseries of parallel teeth 34 running endwise of the block but at an angleto the longitudinal axis thereof (Fig. 4)- The teeth 19 of die 16 aresimilarly arranged, the teeth of one die,v

however, being opposed to the intervening grooves of the other, asappears in Figs. 3

and 7.

As will be understood by those skilled in the art, the angle of the dieteeth with re- 'spect to the longitudinal axis of the die block; thatis, with respect to the direction of travel of the blank, governs thelead of the thread formed on the blank. In the present embodiment thedie blocks areso spaced apart that the tooth crests are separated by adistance less than, and the groove bottoms by aidistance greater than,the diameter of that part of the blank that is to be threaded. As aresult, the outside diameter of the formed thread is greater than wasthe diameter of the blank before threading. The embodiment shown isparticularly adapted to threading cap screws and with the die relationshown, the blanks have an enlarged stem. so that when threaded. theoutside diameter of the threads equals the diameter of the stem.

When the traveling dye 16 is drawn back to the position of Fig. 1. around blank r is placed between the adjacent ends of the dies by hand orby any suitable feeding Fig. 4t shows a cap screw blank having. itspolygonal head above the top edge of the die block, the block having aplain surface 35 corresponding to the stem 36 of the blank that is notto be threaded. Upon the advance movement of die 16, the

blank is rolled between the two dies, that is, the blank revolves on itsown axis and travels along between the dies as the travel ing dieadvances. For a half turn of the blank, the teeth of die 16 form threadportions in half the surface of the blank and the teeth of the die 33form thread portions in the other half of the blank surface. That is,referring to Fig 9 which represents a section through the blank, die

16 for example, has formed thread portions from the point X around topoint Y and die 33, during the same half turn of the around to X. Duringthe next half turn of the blank the half threads formed by the die 16are presented to die 33 and the half threads formed by the die 33 arepresented to die 16 for further formation or finishing or both.Ordinarily the complete thread is roughly formed during the first halfturn or first few half turns, the remainder of the action being in thenature of -a finishining or planishing operation. As a result of the dieaction, by the time the traveling die has 'moved across and beyond theother die. the blank is formed with a com plete finished thread and candrop out from the dies, to be removed in any suitable manner.

While screws have been threaded by rolling blanks between dies in thegeneral manner above described, the threads on rolled screws asheretofore made, have not always been accurate. There has been aconsiderable loss due to so called drunk? threads which will not enterthe standard gauge. These drunk threads are due to a variation from thetrue or theoretical lead of the thread. In the ideal formation of rolledthreads, the blank should start its axial movement and travelingmovement, at the same instant and its axial and traveling movementsshould continue regularly and at the rate for which the dies aredesigned. It sometimes happens, however. that the start of the axialmovement and the-start of the traveling movement are not simultaneous.or the rateof movement is irregular. In other words. there is a certainamount of slippage of the blank with respect to the dies. vAs a resultof this slippage. in

machines heretofore known, the lead of the formed thread varies from thetheoretical lead because that half of the thread forn'led by one die isout of true position when it moves around to the other die andconsequently the teeth of the latter cause the thread to be distortedout oftrue.

Referring to diagrannnatically and in exaggerated manner, the idealconditions. A represents half of the blank and B represents one die. A

represents the same half of the blank after .die and A the same half ofthe blank after a half turn. At the right, the broken lines til) Fig. 7,there is shown.

, compensate for slippage of the blank.

. 33 about its pivot, t

indicate the teeth and grooves of the die, the full lines indicating therelative position of the blank after a half turn and upon slippage. Thatis, formation by tooth b of dieB, when it reaches die C is not inv truemesh with the tooth 0, due to slippage, but has the position (l. Thesame is true, as will be apparent, of all the grooves and crests. As aresult of this out-of-true relation between die and thread, the threadwill be distorted by the die C out of its true lead and the finishedproduct will be inaccurate. I

lhe present invention includes means for permitting a die movementtransverse the direction of the blanks travel, thereby to may beaccomplished for example by so mounting the stationary or non-travelingdie that it may float. Although capable of various constructions, inthat here shown as' an example, the die block 33 is carried by a bearingplate 40 which is-slidable on the face of the die holder 30. As appearsin Fig. 6, the holder 30 has rabbeted top and bottom ledges 41, 42, bywhich the plate 40 is confined but enough clearance is left to permit aslight movement of the die. As shown, the die is pivotally mounted, thepivot being adjacent the end of the die at which the blank starts. Tothis end, secured to the inner face of the plate 40 is a pivot pin43mounted to swivel in a suitable hole inthe die carrier 30.. The dieblock and its bearing plate can thus swing about 'pin 43 as a pivot, theslightly curved end of the die block bearing against a roller 44;.

When and if slippage of the blank occurs, and conditions such asdescribed in connection with Fig. 8 exist, the slippage is compensatedfor b movement of the die moving across the direction of travel of theblank. That is, when the thread of the blank leaving die 16 andapproaching die 33 fails to mesh properly with the latter, the strainsset up, instead of distorting the thread of the blank to give it aninacits pivot to curate lead, cause the die 33 to swing 011 permit thethread and die teeth to have accurate'registry ormesh. In other words,the die changes its-relative position to compensate for the change inthe relative position of the blank, and as a result the thread is notdistorted.

With the construction described the threads produced on a succession ofblanks are uniformly accurate within the limits of deviation allowed bytrade standards.

It is desirable to have the floating die in of therolling normalposition at the start of the blank and during the first part of theblank traveL. entirety, therefore, includes means for resettingthedie tonormal or initial position,

the groove a, under This e free end of the die 63 by means of a nut 64;is a The invention in its if it has moved, and looking it in suchposition for a predetermined period with respect to the blank travel.Although capable of various constructions, in that here shown as anexample, the end of the bearing plate 40 has a wedge-shaped notchadapted to be entered by a wedge 51. This wedge is formed on the end ofa plate 52 slidable in a guide housing 53 on the die carrier 30. On theother end of the plate 52 is an arm 54 through Which passes a rod 55slidable in an open-sided bracket 56. On the outer end of rod 55 is anut 57 and between the nut and arm 54 is a coiled spring 58. When therod 55 is pulled in the direction in which" wedge 51 points (to the leftin Figs. 4.and 5), the force of spring 58 causes movement of arm 54,whereby the wedge is moved towardthe notch 50. Upon resistance beingencountered by the wedge, spring 58 is compressed until, the coils beingclosed, nut, spring'and arm move as a unit to force the notch. Duringthis movement, if the die unit, which includes plate 40, has moved outof normal position, the wedge 51 acting against the side ofnotch 50 camsthe die unit back to normal position. Further, it will beobserved, aslong as the wedge remains in the notch the die unit is locked againstmovement. This position is shown in Fig. 4.

While the means for actuating the rod 55 may be varied, it mayconveniently be accomplished by the movement of the traveling die andmay make possible a release of the wedge after a predetermined dietravel. constructions, in the present embodiment, secured to the forwardend of the die ,carrier 15 is a bracket 60 havingan arm 61 extendingtoward, die 33 (Figs. 2 and 3). This arm is bent to have its endparallel with and above die 33 and this end 62 is provided with. a slot63. Set in the slot pin 65 carrying a roller 66. During the idle backstroke of the traveling die, the roller 66 engages an elongated lever67, fulcrumed on the die carrier 41 and pinned to the end of rod 55.When the wedge 51 is in release position the lever 67 has the positionshown in broken lines similarly indicated. As the roller advances to theleft it pushes down the lever whereby the rod 55 is given the movementabove described and the wedge is forced int-o the .notch 50 to re-setthe die if it is moved.

the wedge completely into Although capable of various (Fig. 4), theroller being its lock so as to be able to float as described. To thisend, in the exemplification shown,

. there is provided meansfor giving a re- I 70 makes engagement with arm54: but

thereafter this engagement causes a simultaneous movement of the arm towithdraw wedge 51 from notch 50. During this movement of rod 55, spring58 is free to re-expand to its former position. A collar 7 0 pinned torod 55, acts as a stop against bracket 56 to limit the release movementof therod. This position of the parts is shown in Fig. 5, in which, forsimplicity of illustration, the teeth of die block 33 have been omitted.

If it is desired to vary the time, with respect tothe travel of the die16 and blank, at which the die 33 is permitted to float, the pin may bemoved along its slot. By this adjustment, the lever 67 will be releasedearlier or later with respect to the start of the operation, as may bedesired.

The. dies here illustrated are for forming right hand threads and thecompensating movement of the floating die is upward, that is, toward thehead of the blank. The invention in its entirety includes means forpreventing a transverse die movement under the force of gravity. Thismeans may conveniently be yieldable upon a predetermined force so thatthe die may have a compensating movement downward in case die blocks fora left hand thread are used.

Although capable of various constructions, in the embodiment shown, onthe bearing plate a0 is a housing 71. In this housing is a plunger 72each end of which extends through the end ofthe housing (Fig. 4). Coiledabout plunger 72 is a spring 73 one end of which bears against thehousing, the other end against a collar 74 on the plunger 72. The lowerend of plunger 72 in normal position engages the bottom ledge 42 of thedie carrier 30. Any tendency of the die block to move down by gravity isresisted by the spring 73. Should there be sufficient force applied,however, to overcome the force of spring 73, the die block can movedownward against the compression of the spring. Thus, if left handedthreads are being rolled the die can have a compensating movement, inthis instance downward.

The operation of the machine shown will be clear from the above withoutfurther description.

What I claim is:

1. The combination with two dies for rolling theads on, a blank whichrolls between the dies as the thread is formed, of means for ermitting adie movement transverse the irection of travel of the blank, saidmovement compensating for sli page of the blank with respect to the diesuring the thread forming operation, whereby accuracy in forming thethread is increased, and means for re-setting the die, after suchcompensating movement, in an initial position.

2. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for moving one of saiddies with respect to the other to cause rolling of the blank between thedies, means for mounting the other die to be movable transverse thedirection of travel of the blank, and means for re-setting the seconddie in an initial position after any such transverse movement.

3. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for reciprocating one ofsaid dies with respect to the other to cause rolling of the blankbetween the dies on the advance stroke, means for mounting the other dieto be movable transverse the direction of travel of the blank, and meansoperated by the movement of the first die on its return stroke forresetting the second die in initial position.

4. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, and means (a) for permitting adie movement transverse the direction of travel of the blank during apart of the blank movement, said die movement compensating for slippageof the blank with respect tothe dies, and (b) for preventing said diemovement during the first part of the travelof the blank.

5. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for causing relativemovement between the dies, means for mounting at least one die to bemovable transverse the direction of travel of the blank, and'meansdependent on the relative position of the two dies for locking thetransversely movable die against such movement and for releasing itbefore the termination of the passage of the blank between the dies.

6. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for movthe blank,locking-.means'for holding the second die against su'ch transversemovement, and means for causing said locking means to release the dieafter a predetermined travel of the first die.

7, In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for reciprocating onedie with respect to the other 'to cause the blank, on theadvance stroke,to roll between the dies, the second die being mounted for a diemovement transverse the direction of travel of the blank, and meansincluding a part moving with the first die, for (a) resetting theseconddie in initial position upon the idle return stroke of the travelingdie, (12) looking the second die in initial position, and (0) releasingthe die from its look upon a predetermined travel of the reciprocatingdie upon its advance stroke.

8. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for reci rocating onedie with respect to the ot er to cause the blank, on the advance stroke,to be rolled between the dies, the second die being mounted for a diemovement transverse the direction of travel of the blank, and meansincluding a moving with the reciprocating die,-for (a) resetting thesecond die in initial position u on the idle return stroke of thetraveling ie, (6) locking the second die in initial position, and (a)releasing thedie from its look upon ,a predetermined travel of thereciprocating die upon its advance stroke, a part ofsaid resetting,locking and releasing means being adjustable to vary the time withrespect to the die travel at which the second die is released.

9. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread is formed, means for causing relativemovement between the dies so to cause a blank to berolled between them,means for mounting one die to have a movement transverse the directionof travel of the blank, and means for causing said die to belockedagainst such transverse movement during a variable portion of theblankrolling relative movement of the dies.

10. In combination, two dies for rolling threads on a blank which rollsbetween the dies as the thread'is formed, a movable die W carrier forone ofsaid dies, at stationary'die carrier, a die unit comprising thesecond die mounted in said stationary carrier to have a movementtransverse the direction of travel of the blank, said die unit and its Ishaped to fit said notch, a lever, an operative carrier having the one awedge and the other a Wedge-shaped notch, and means for causing relativemovement between said Wedge and notch to place the same into and outof'interlocking relation.

11. In combination, two sides for rolling threads on a blank which rollsbetween the dies as the thread is formed, a movable die carrier for oneof said dies, a stationary die carrier, a die unit comprising the seconddie mounted in said stationary carrier tohave a movement transverse thedirection of travel of the blank, said die unit having a Wedge-shapednotch, a wedge shaped to fit said notch and carried by the die carrier,and means for moving the wedge into and out of the notch.

12. In combination, a movable die carrier, a die block mounted therein,a stationary die carrier, a die unit, comprising a second die block,mounted in said stationary die carrier to have a movement transverse thedirection of travel of the blank, said die unit having a wedge-shapednotch, a wedge connection between said lever and the wedge, a spring fornormally holding said wedge out of the notch, an element moved by themovable die carrier for engaging said lever to cause the wedge to hemoved into the notch, and means for moving the movable die carrier tocause a blank to be rolled between the dies.

13. In combination, a movable die carrier, a die block mounted therein,a stationary die carrier, a ,die unit, comprising a die block, mountedin said stationary die carrier to have a movement transverse thedirection of travel of the blank, said die unit having a wedge-shapednotch, a ,wedge shaped to fit said notch, a lever, an operativeconnection between said lever and the wedge, a spring for normallyholding said wedge out of the notch, an adjustably positioned elementmoved by the'movable die carrier for engaging said lever to cause thewedge to be moved into the notch, and means for moving the movabledie-carrier to cause a blank to be rolled between the dies.

14. In combination, 'two dies for rolling threads on a blank which rollsbetween the 115 dies as the thread is formed, means for causing relativemovement between the dies to cause a blank to be rolled between them,one die being mounted to be movable transverse the direction of travelof the blank, and means whereby thelast named die may be held againstsuch transverse movement at the start of and during a predeterminableportion of the blank-rolling relative movement of the dies.

In testimony whereof, I have hereunto set n1 hand.

y GLENN H. WAYNE.

